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Impact of Pre-ozonation on Distillery Effluent Degradation in a Constructed Wetland System
| Content Provider | Semantic Scholar |
|---|---|
| Author | Green, Jeffrey |
| Copyright Year | 2007 |
| Abstract | Distilleries are an example of an agricultural industry that generates large volumes of wastewater. These wastewaters are heavily polluted, and due to the seasonal nature of the product, the amount and composition of the wastewater may exhibit major daily and seasonal variations. Wine-distillery wastewaters (WDWWs) typically are acidic (pH 3.5 5.0) and have a high organic content (sugars, alcohol, proteins, carbohydrates and lipids), a COD range of 10 000 – 60 000 mg.L, have a high suspended solids content as well as containing various inorganic compounds. Additionally refractory compounds present in these wastewaters, such as polyphenols, can be toxic for biological processes, making the selection of a suitable treatment process problematic. Wetlands have been shown to be a feasible treatment for effluent originating from wine, however, they are normally used as a secondary treatment method and not well suited for high volume, high COD (> 5 000 mg.L) wastewaters. Ozone has been successfully used as a pre-treatment for WDWW due to its oxidising capabilities to partially biodegrade organics and non-biodegradable organics, and reduce polyphenols, which results in an increase in biodegradability. Currently a wetland system is being used on its own at a distillery to treat wastewater from a series of stabilisation dams, but the legal requirement for discharge into a natural resource (COD < 75 mg.L) is not being met. Additional treatments suited for WDWW are therefore being considered. Wine-distillery wastewater was characterised and found to show a large variation over time (COD ranging from 12 609 21 150 mg.L). Ozonation of WDWWs was found to be effective in decreasing COD over a wide range of organic loads. For pre-wetland wastewater from the distillery, an average COD reduction of 271 mg COD.g O3 was found, and for post-wetland effluent, an average of 103 mg COD.g O3. The effect of ozone on the biodegradability of the wastewater was monitored by activity tests, and a low ozone dose (200 400 mg O3.L) was found to increase activity in terms of biogas, methane and cumulative gas volumes. By showing an increase in the biodegradability of WDWW, it was concluded that ozone has potential as a pre-treatment step to increase the effectiveness of a biological wetland system. Lab-scale wetlands were used in trials to determine the effect of preand postozonation on WDWW. It was found that the efficiency of the wetland receiving the preozonated “off-season” WDWW (2 200 mg COD.L) had a higher COD reduction (73%) than the wetland fed with untreated (62% COD reduction) WDWW, and the total polyphenol content was reduced by 40 and 31%, respectively. Treatment efficiency in |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://scholar.sun.ac.za/bitstream/handle/10019.1/1650/Green,%20J.pdf?sequence=1 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
